WASHINGTON • Billionaire businessman Donald Trump inched closer to the US Republican presidential nomination after easily out- distancing his rivals in the Nevada caucus, giving him his third win in four early nominating contests.

Broadcast networks called the state for Mr Trump almost immediately after voting ended, with the state Republican Party confirming the victory soon after.

With returns still being tabulated yesterday, Senator Marco Rubio of Florida was in second place, with Mr Ted Cruz, a senator from Texas, coming in third.

"This is an amazing night," Mr Trump told cheering supporters during a victory speech in Las Vegas.

Tuesday's result underscored the enormous challenge his rivals face as the candidates head into next week's all important "Super Tuesday" contests involving 11 states.

Less than a month ago, the Republican establishment was hoping Mr Trump's insurgent candidacy would stall after he lost the opening nominating contest in Iowa to Mr Cruz.

"If you listen to the pundits, we weren't expected to win too much, and now we're winning, winning, winning the country," Mr Trump said at the rally.

Polls suggest he will do well in many of the Super Tuesday states, placing further pressure on Mr Cruz, Mr Rubio and Ohio governor John Kasich, another presidential candidate who was not a factor in Nevada, to come up with counter- measures quickly.

"These guys have to figure out how to turn their fire on Trump," said Mr Ford O'Connell, a Republican strategist in Washington. Absent that, he said: "Which one is going to get out of this field?"

In the run-up to Nevada, most of Mr Trump's rivals left him alone, preferring to tussle with each other in a bid to be the last surviving challenger to the front runner.

Mr Rubio, who has emerged as the Republican establishment's favourite to derail Mr Trump's progress, can take some solace in finishing second. But that also has to be viewed as somewhat of a setback, considering he had frequently campaigned in Nevada, having lived there as a child. A Cuban-American, he had attempted to rally the support of the state's large Latino population.

Mr Rubio had also benefited from the departure last Saturday of Mr Jeb Bush from the race. That brought an influx of new funds, a bevy of endorsements, and a wealth of media attention. But none of it was enough to overtake Mr Trump.

An ecstatic Mr Trump said his win was broad-based.

"We won the evangelicals. We won with young. We won with old. We won with highly educated. We won with poorly educated," he said. "I love the poorly educated. We're the smartest people. We're the most loyal people."

Although the caucus in Nevada is not expected to have a significant impact on the overall race - only 30 delegates or slightly more than 1 per cent of the total are up for grabs - it was the first contest for the Republicans in the US west.

Dr Dan Lee, assistant professor of political science at the University of Nevada, Las Vegas, said the Nevada caucus was taking place as mainstream Republicans are grudgingly accepting the fact that Mr Trump may well end up being the party's nominee, given his winning streak.

"A lot of Republicans - especially the Republican establishment, professionals, governors - don't really want Trump to win the nomination," Dr Lee said. "They want to get Cruz out and have Rubio go against Trump."

The real estate magnate dished out his trademark rhetoric ahead of Tuesday's vote, comparing Mr Cruz to a "soft, weak, little baby" at a rally. "But for lying, he's the best I've ever seen," he added.

Mr Cruz fired back, accusing him of consistently vacillating on issues and saying his insults showed how rattled he was.

REUTERS, AGENCE FRANCE-PRESSE, BLOOMBERG